Terrific value. The only question is, how well that 4GB of VRAM will hold up against cards that have 8Gb. Even some games as old as 3 years+ can easily breach the 4Gb usage mark when you crank things to the max.
@BARRYV88 Probably reasonably well. I installed BO4 on my laptop today, and i was genuinely surprised to find i could run it with ultra textures (everything else medium or low, mostly medium) and achieve an almost stable 60fps. This is a mobile 1050 2GB we're talking about. My guess is 4GB will be enough for 1080p for a few years at least. By the time is isn't enough cards that only have 4GB will probably be obsolete or at least low end.
An RX 580 is generally at a similar performance level to a GTX 1060 6GB. So a 1070 is going to be faster, probably by around 30-35% in most games bound by graphics card performance. Then again, we are comparing a card that's been selling for around $200 to one that's around $350, so obviously a performance difference should be expected. On a performance-per-dollar basis though, the 580 will offer more performance for the money, since the 1070 tends to cost nearly twice as much, unless you are buying a used one or something.